Re: [Xen-devel] Question about the XEN platform pci

["Wu, Bob" <Bob.Wu@xxxxxxx>]

Subject: Re: [Xen-devel] Question about the XEN platform pci

The INTx interrupt of this platform device can be used by Xen in HVM case to 
notify the guest of pending events in the event channel. However that's usually 
not used in favor of vector callbacks support in Xen where a vector is injected 
directly to the vCPU bypassing LAPIC.

(that said, the platform-pci driver in linux is actually broken when vector 
callbacks are not used anyway)

I also think that the grant-table lives on this PCI device MMIO BAR (?!)

If you looked at hw/i386/xen/xen_platform.c in QEMU source , you will get a 
general idea what this device is supposed todo (like logging to syslog stuff 
for example).

That said the platform device is really not fully utilized anyway in Linux.


Yes, the answer is my expected, so the biggest reason of platform PCI still 
existing in the kernel code is that INTx interrupt or vector callback will need 
the help of it.
Thanks Karim.
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